<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1, user-scalable=no">
    <meta http-equiv="X-UA-Compatible" content="ie=edge,chrome=1">
    <meta name="author" content="程月">
    <title>下拉菜单</title>
    <style>
    *{
        box-sizing: border-box;
    }
    body{
        margin: 0;
    }
    ul{
        margin: 0;
        padding: 0;
        list-style: none;
    }
    a{
         text-decoration:none;
         font-size:inherit;
         color:inherit;
    }
    nav{
        width: 100%;
        height: 50px;
        background-color: #eee;
    }
    ul{
        width: 800px;
        margin: 0 auto;
        height: 50px;
        display: flex;
        justify-content: space-around;
        background-color: #aaa;
        color: #fff;
         line-height: 50px; 
        text-align: center;
    }
    ul li{
        position: relative;
    }
    ul li>a{
        padding: 0 25px;
        font-size: 18px;
    }
    div{
        width: 100%;
        position: absolute;
         top: 49px; 
        border: 1px  solid #aaa;
        color: #bbb;
         display: none; 
    }
    </style>
</head>
<body>
    <nav>
        <ul>
            <li>
                <a href="#" class="title">公司简介</a>
                <div>
                    <p><a href="#">概况介绍</a></p>
                    <p><a href="#">发展历史</a></p>
                    <p><a href="#">公司实力</a></p>
                </div>
            </li>
            <li>
                <a href="#" class="title">产品介绍</a>
                 <div>
                    <p><a href="#">教育研发</a></p>
                    <p><a href="#">软件教育</a></p>
                    <p><a href="#">天使投资</a></p>
                </div>
            </li>
            <li>
                <a href="#" class="title">联系我们</a>
                 <div>
                    <p><a href="#">公司地址</a></p>
                    <p><a href="#">联系方式</a></p>
                    <p><a href="#">投资加盟</a></p>
                </div>
            </li>
            <li>
                <a href="#" class="title">人才招聘</a>
                 <div>
                    <p><a href="#">JAVA招聘</a></p>
                    <p><a href="#">HTML5招聘</a></p>
                    <p><a href="#">PHP招聘</a></p>
                </div>
            </li>
        </ul>
    </nav>
    <script src="./jquery.js"></script>
</body>
</html>
<script>
    $('li').hover(function(){
        $(this).css('color','pink').css('text-decoration','underline');
        $('div').eq($(this).index()).css('display','block');
    },function(){
        $(this).css('color','#fff').css('text-decoration','none');
         $('div').eq($(this).index()).css('display','none');
    });

    $('div a').hover(function(){
        $(this).css('text-decoration','underline');
    },function(){
        $(this).css('text-decoration','none');
    });
</script>